Booting LiveCD Without X

LiveCD environments can usually be helpful for testing, but if you're troubleshooting a problem where X does not start up, that makes it difficult to retrieve the log files and other such things. But it can be done:

This will try to start X and log some information about the active screen resolution to the file xrandr.log before it stops X again.

4. Start up an X session like this:

startx

or

/usr/X11R6/bin/X :0

Bypassing/Disabling gdm

Option 0 - Automatic Login Through gdm

You can set up gdm to automatically log in a user either via System > Administration > Login Window > Security > Enable Automatic Login, or by editing the /etc/gdm/gdm.conf configuration file, and set AutomaticLoginEnable=true and AutomaticLogin=<username>.

Option 1 - Turning off GDM after bootup

Switch to a tty (ctrl+alt+F1) or use ssh, log in, and shut off GDM for the current session like this:

$ sudo /etc/init.d/gdm stop

Check to see if you have any remaining X sessions running, and if so, kill them:

This option is appropriate if your system boots up okay other than X, such that you can either ssh into it or access a tty. If gdm is completely locking up your system during boot up, then see the next options.

Option 2 - Temporarily disabling GDM

To disable gdm from running during boot, you can either boot with the "text" boot parameter or disable the rc service like this:

sudo update-rc.d gdm stop 2 3 4 5 .

Please note that there is a dot at the end. This is essential.

Then to re-enable it later,

sudo update-rc.d gdm start 30 2 3 4 5 . stop 01 0 1 6 .

This option is useful if gdm or X locks up the system during boot, or if you wish to run X in complete isolation from gdm.

Option 3 - Removing GDM entirely

In order to disable X from starting when booting the system, you can simply remove gdm from the init scripts:

sudo update-rc.d -f gdm remove

and, to enable X again when booting:

sudo update-rc.d gdm defaults

This option is probably only useful if you know you want to always boot X manually, and want to eliminate graphical booting entirely.

Starting up X manually

Option 1: startx script

From the text console, run

startx

Option 2: Starting X directly

From the text console with no other X running, you can invoke X directly, bypassing all the startup scripts and stuff:

/usr/X11R6/bin/X :0

If you're running multiple X sessions, use :1, :2 for second, third sessions. (For debugging, it's usually easiest to stick with a single X session invoked from the console.)

X supports a wide variety of other startup flags that can be of value for debugging problems or working around issues. See man xorg for a comprehensive list. Here's a few particularly useful ones:

-allowMouseOpenFail

Allow the server to start up even if the mouse device can't be opened or initialised.

-ignoreABI

Bypasses server's ABI version check when loading e.g. binary drivers (-fglrx/-nvidia). This option should be used with care.

-keeptty

Prevent the server from detaching its initial controlling terminal. This option is only useful when debugging the server. Not all platforms support (or can use) this option.

-showopts

For each driver module installed, print out the list of options and their argument types.